CHAPTER 6 CONCLUSION 6.1. Conclusion - core.ac.uk · CHAPTER 6 CONCLUSION . 6.1. Conclusion . From...

50

CHAPTER 6

CONCLUSION

6.1. Conclusion

From the research that is done in PT. Purinusa

Ekapersada to get interval of preventive maintenance

based on cost minimization, the conclusion are:

1. Optimum interval preventive maintenance for

hotplate part is 24 hour with Rp 196 and reduce

cost 76.2 %

2. Optimum interval preventive maintenance for

mechanical repair is 23 hour with Rp 45 and reduce

cost 92.4%

6.2. Suggestion

1. Corrective maintenance change into preventive

maintenance to reduce cost.

2. Detail for down machine record must be increased,

for daily data convert into hour data.

51

REFERENCE

Anjar, A., 2010, Pergantian Preventif Komponen Pada

Mesin Seamer dan Capper Berdasarkan Kriteria

Minimasi Downtime Studi Kasus Di PT.Zeta Argo

Corporation, Fakultas Teknologi Industri UAJY,

Yogyakarta.

Ariestania, S., 2010, Penentuan Waktu Overhaul Optimum

Pada Mesin Cetak di PT. Macanan Jaya Cemerlang,

Klaten, Fakultas Teknologi Industri UAJY,

Yogyakarta.

Assauri, S., 1993, Manajemen Produksi dan Operasi, Lembaga

Penerbit Fakultas Ekonomi Universitas Indonesia (FE-UI),

Jakarta.

Corder, A., diterjemahkan Hadi, K., 1992, Teknik Manajemen

Pemeliharaan, Erlangga, Jakarta.

Dhillon, B.S., 1997, Reliability Engineering in System

Design and Operation, Van Nostrand Reinhold Company,

Inc., Singapore.

Dwiyanti, S., 2005, Penentuan Interval Pengantian Preventif

Jarum Jahit dengan Meminimasi Ekspetasi Biaya Total

Penggantian, Fakultas Teknologi Industri UAJY,

Yogyakarta.

Ebeling, C.E., 1997, An Introduction to Reliability and

Maintainability Engineering, The Mc-Graw Hills Companies

Inc., Singapore.

Gaspersz, V., 1992, Analisis Sistem Terapan: Berdasarkan

Pendekatan Teknik Industri, Penerbit “Tarsito”, Bandung.

52

Jardine, A.K.S., 1973, Maintenance, Replacement, and

Reliability. Pitman Publishing Corporation, Canada.

Kelton, W.D., 2002, Simulation With Arena, 2nd ed, The Mc-

Graw Hills Companies Inc., USA.

Nurcahyo, R., 2006, Modern Management and Spare Part

Management, Quality Buana Insani Consulting, Jakarta.

53

Attachment 1 Detail of Maple Software for Hotplate

Weibull Distribution

ctp:=evalf((1422988/(24*60)*0.19));

ctp := 10870.04722

ck:=44946+ctp

;ck := 55816.04722

mean:=54.7;

mean := 54.7

be:=19;

be := 19

al:=0.542;

al := .542

fung:=(al*(be^(-al))*((t-23.8)^(al-1))*

(exp(-((t-23.8)/be)^al)));

fung := .1098790345/(t-23.8)^.458*

exp(-(1/19*t-1.252631579)^.542)

Rt:=(int(fung,t=tp..infinity));

Rt := int(.1098790345/(t-23.8)^.458*exp(-(1/19*t-

1.252631579)^.542),t = tp .. infinity)

ft:=(1-Rt);

ft := 1-int(.1098790345/(t-23.8)^.458*exp(-

(1/19*t-1.252631579)^.542),t = tp .. infinity)

cost:=((ctp*Rt)+(ck*ft));

cost := -44946.00000*int(.1098790345/(t-

23.8)^.458*exp(-(1/19*t-1.252631579)^.542),t = tp ..

infinity)+55816.04722

cycle1:=((tp)*Rt);

cycle1 := tp*int(.1098790345/(t-23.8)^.458*exp(-

(1/19*t-1.252631579)^.542),t = tp .. infinity)

et:=(int((t-23.8)*(fung),t=23.8..tp));

Cost of Corrective

Maintenace

Mean

Cumulative

Distribution

Function

Cost of Preventive

Maintenace

Beta

Alpha

Reliability

Probability Distribution Function

Total Cost

54

et := int(.1098790345*(t-23.8)^.542*exp(-(1/19*t-

1.252631579)^.542),t = 23.8 .. tp)

cycle2:=((et)*(ft));

cycle2 := int(.1098790345*(t-23.8)^.542*exp(-

(1/19*t-1.252631579)^.542),t = 23.8 .. tp)*(1-

int(.1098790345/(t-23.8)^.458*exp(-(1/19*t-

1.252631579)^.542),t = tp .. infinity))

cycle:=(cycle1+cycle2)+23+0.19;

cycle := tp*int(.1098790345/(t-23.8)^.458*exp(-

(1/19*t-1.252631579)^.542),t = tp ..

infinity)+int(.1098790345*(t-23.8)^.542*exp(-(1/19*t-

1.252631579)^.542),t = 23.8 .. tp)*(1-

int(.1098790345/(t-23.8)^.458*exp(-(1/19*t-

1.252631579)^.542),t = tp .. infinity))

Cpu:=(cost/cycle);

Cpu := (-44946.00000*int(.1098790345/(t-

23.8)^.458*exp(-(1/19*t-1.252631579)^.542),t = tp ..

infinity)+55816.04722)/(tp*int(.1098790345/(t-

23.8)^.458*exp(-(1/19*t-1.252631579)^.542),t = tp ..


1.252631579)^.542),t = 23.8 .. tp)*(1-

int(.1098790345/(t-23.8)^.458*exp(-(1/19*t-

1.252631579)^.542),t = tp .. infinity)))

dCpu:=diff(Cpu,tp);

dCpu := 4938.623085/(tp-23.8)^.458*exp(-(1/19*tp-

1.252631579)^.542)/(tp*int(.1098790345/(t-

23.8)^.458*exp(-(1/19*t-1.252631579)^.542),t = tp ..


1.252631579)^.542),t = 23.8 .. tp)*(1-

int(.1098790345/(t-23.8)^.458*exp(-(1/19*t-

1.252631579)^.542),t = tp .. infinity)))-(-

Cycle Time

55

44946.00000*int(.1098790345/(t-23.8)^.458*exp(-(1/19*t-

1.252631579)^.542),t = tp ..

infinity)+55816.04722)/(tp*int(.1098790345/(t-

23.8)^.458*exp(-(1/19*t-1.252631579)^.542),t = tp ..


1.252631579)^.542),t = 23.8 .. tp)*(1-

int(.1098790345/(t-23.8)^.458*exp(-(1/19*t-

1.252631579)^.542),t = tp ..

infinity)))^2*(int(.1098790345/(t-23.8)^.458*exp(-

(1/19*t-1.252631579)^.542),t = tp .. infinity)-

.1098790345*tp/(tp-23.8)^.458*exp(-(1/19*tp-

1.252631579)^.542)+.1098790345*(tp-23.8)^.542*exp(-

(1/19*tp-1.252631579)^.542)*(1-int(.1098790345/(t-

23.8)^.458*exp(-(1/19*t-1.252631579)^.542),t = tp ..

infinity))+.1098790345*int(.1098790345*(t-

23.8)^.542*exp(-(1/19*t-1.252631579)^.542),t = 23.8 ..

tp)/(tp-23.8)^.458*exp(-(1/19*tp-1.252631579)^.542))

solve (dCpu=0,tp);

Error, (in solve) cannot solve expressions with,

int(219758069/2000000000/(t-119/5)^(229/500)*exp(-

(1/19*t-1252631579/1000000000)^(271/500)),t = tp ..

infinity), for, tp

56


Weibull Distribution with Numeric Method

ctp:=evalf((1422988/(24*60)*0.19));

ctp := 10870.04722

ck:=44946+ctp

;ck := 55816.04722

mean:=54.7;

mean := 54.7

be:=19;

be := 19

al:=0.542;

al := .542

fung:=(al*(be^(-al))*((t-23.8)^(al-1))*

(exp(-((t-23.8)/be)^al)));

fung := .1098790345/(t-23.8)^.458*

exp(-(1/19*t-1.252631579)^.542)

for tp from 24 by 1 to 264 do tcoba:=tp;

Rt:=evalf(int(fung,t=tp..infinity));

ft:=evalf(1-Rt);

cost:=evalf((ctp*Rt)+(ck*ft));

cycle1:=evalf((tp)*Rt);

et:=evalf(int((t-23.8)*(fung),t=23.8..tp));

cycle2:=evalf((et)*(ft));

cycle:=evalf(cycle1+cycle2)+23+0.19;

Cpu:=evalf(cost/cycle);

od;

Reliability


Total Cost

Cycle Time

Numeric method

Cost of Corrective

Maintenace

Mean

Cumulative

Distribution

Function

Beta

Alpha

57


Lognormal Distribution with Numeric Method

ctp:=evalf(1422988/(24*60)*0.19);

ctp := 187.7553611

ck:=(44946+ctp);

ck := 45133.75536

mean1:=59.6;

mean1 := 59.6

sd1:=530;

sd1 := 530

mean:=ln((mean1^2)/(sqrt((sd1^2)+(mean1^2))));

mean := 1.896150966

sd:=sqrt(ln(((sd1^2)+(mean1^2))/(mean1^2)));

sd := 2.093563760

fung:=(1/(sd*(t-23)*sqrt(2*3.14)))*exp(-(ln(t-23)-

mean)^2/(2*(sd^2)));

fung := .1906048671/(t-23)*exp(-.1140768763*(ln(t-

23)-1.896150966)^2)

for tp from 24 by 1 to 264 do

tcoba:=tp;

rt:=int(fung,t=tp..infinity);

ft:=1-rt;

cost:=(ctp*rt)+(ck*ft);

cycle1:=(tp)*rt;

et:=evalf(int((t-23)*(fung),t=23..tp));

cycle2:=(et)*(ft);

cycle:=cycle1+cycle2+23+0.19;

mincost:=(cost/cycle);

od;

58

Attachment 4 Detail of Maple Software for Mechancal

Repair Exponential Distribution

ctp:=evalf(1422988/(24*60)*1.2617);

ctp := 1246.794416

ck:=(44946+ctp);

ck := 46192.79442

mean:=55.3;

mean := 55.3

fung:=1/mean*exp(-(t-22)/mean);

fung:=.1808318264e-1*exp(-.1808318264e-

1*t+.3978300181)

Rt:=int(fung,t=tp..infinity);

Rt := exp(-.1808318264e-1*tp+.3978300181)

ft:=1-Rt;

ft := 1-exp(-.1808318264e-1*tp+.3978300181)

cost:=(ctp*Rt)+(ck*ft);

cost:=-44946.00000*exp(-.1808318264e-

1*tp+.3978300181)+46192.79442

cycle1:=(tp)*Rt;

cycle1:=tp*exp(-.1808318264e-1*tp+.3978300181)

et:=evalf(int((t-22)*(fung),t=22..tp));

et:=-1.*tp*exp(-.1808318264e-1*tp+.3978300181)-

33.30000000*exp(-.1808318264e-

1*tp+.3978300181)+55.30000000

cycle2:=(et)*(ft);

cycle2:=(-1.*tp*exp(-.1808318264e-

1*tp+.3978300181)-33.30000000*exp(-.1808318264e-

1*tp+.3978300181)+55.30000000)

*(1-exp(-.1808318264e-1*tp+.3978300181))

cycle:=cycle1+cycle2+22+1.2617;

Cost of Corrective

Maintenace

Mean

Reliability



59

cycle:=tp*exp(-.1808318264e-1*tp+.3978300181)+

(-1.*tp*exp(-.1808318264e-1*tp+.3978300181)-

33.30000000*exp(-.1808318264e-

1*tp+.3978300181)+55.30000000)*

(1-exp(-.1808318264e-1*tp+.3978300181))+22

Cpu:=evalf(cost/cycle);

Cpu:=(-44946.00000*exp(-.1808318264e-

1*tp+.3978300181)+46192.79442)/(tp*exp

(-.1808318264e-1*tp+.3978300181)+(-1.*tp*exp

(-.1808318264e-1*tp+.3978300181)-33.30000000*

exp(-.1808318264e-1*tp+.3978300181)+55.30000000)*(1.-

1.*exp(-.1808318264e-1*tp+.3978300181))+22.)

solve(dCpu=0,tp);

-2.266313005+34.01789361*I

plot(Cpu,tp=22..527);

60

Attachment 5 Distribution Summaries for Hotplate part

with Arena Input Analyzer

Distribution Summary of Weibull Distribution

Distribution: Weibull

Expression: 23 + WEIB(19, 0.542)

Square Error: 0.003651

Data Summary

Number of Data Points = 70

Min Data Value = 23.8

Max Data Value = 264

Sample Mean = 54.7

Sample Std Dev = 45.2

61

Distribution Summary of Lognormal Distribution

Distribution: Lognormal

Expression: 23 + LOGN(59.6, 530)


Data Summary




Sample Mean = 54.7

Sample Std Dev = 45.2

62

Attachment 6 Distribution Summary for Mechanical Part

with Arena Input Analyzer

Distribution: Exponential

Expression: 22 + EXPO(55.3)


Data Summary




Sample Mean = 77.3

Sample Std Dev = 84

63

Attachment 7 Corrugator Machine

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